Spatial learning by rats across visually disconnected environments

Abstract

Experiments were designed in which some properties of spatial representations in rats could be examined, Adult subjects were trained to escape through a hole at a fixed position in a large circular arena (see Schenk, 1989). The experiments were conducted in the dark, with a limited number of controlled visual light cues, in order to assess the minimal cue requirement for place learning. Three light cues identical in shape, height, and distance from the table were used. Depending on the condition, they were either permanently on or alternatively on or off, contingent on the position of the rat in the field. Two questions were asked: (1) How many identical visual cues were necessary for spatial discrimination in the dark, and (2) could rats integrate the relative positions of separate cues, under conditions in which the rat was never allowed to perceive all three cues simultaneously. The results suggest that rats are able to achieve a place discrimination task even if the three cues necessary for efficient orientation can never be seen simultaneously. A dissociation between the discrimination of the spatial position of the goal and the capacity to reach it by a direct path suggests that, with a reduced number of cues, prolonged locomotion might be required for accurate orientation in the environment. 16

The HIV-1 transgenic rat model of neuroHIV

“…Although the task is simple – the animals must locate a hidden platform to escape water – there are several strategies that rats can use to search for and remember the location of the platform for an efficient escape. Rats appear to have a preference for the use of visual landmark cues when available (Hodges 1996), but they can learn the task even in the dark (Rossier, Grobéty et al 2000). Because HIV-1Tg rats are born with opaque cataracts, we conducted several studies investigating the performance of HIV-1Tg rats in a modified water maze that minimizes visual cues.…”

Parallel processing of information about location in the amygdala, entorhinal cortex and hippocampus

“…Lesions of the hippocampal system impaired performance on the win‐shift task (Olton et al, , ), in which rats enter each maze arm once to obtain the morsel of food located there. To avoid re‐entering arms the rats must remember which arms they have entered (working memory) and to do that they must be able to discriminate among the arms by learning their relationships to the spatial cues in the maze environment (Zoladek and Roberts, ; Suzuki et al, ; Eichenbaum et al, ; Shapiro et al, ; Rossier et al, ). Furthermore, after consuming the food in an arm a rat must be able to process a change in the meaning of the spatial cues associated with that arm from "food available" to "no food available".…”

Olfactory and/or visual cues for spatial navigation through ontogeny: Olfactory cues enable the use of visual cues.

“…To answer these questions, we trained four age groups in three main conditions. The first condition allowed rats to use a configuration of three discrete visual light cues (Rossier, Grobe ´ty, & Schenk, 2000). The second provided a configuration of five olfactory cues that were dissociated from the five possible escape positions.…”